This application claims the priority of German application 197 07 074.4 filed in Germany on Feb. 22, 1997, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to an opening device for an open-end spinning machine comprising an opening roller having combing structure, which opening roller rotates in a chamber of a housing connected to a vacuum source. The opening roller comprises a sealing surface, to which is arranged a sealing lip of a flexible sealing ring concentrically arranged with respect to the opening roller and supported in the housing, which sealing ring seals the chamber against the open atmosphere.
In the case of an opening device of this type (British patent 1,309,206), the sealing ring is a component part of a labyrinth seal, with which a lateral wall of the opening roller is sealed off against a corresponding side wall of the housing. The sealing lips of the sealing ring are so formed, that either with the lateral wall of the opening roller or the lateral wall of the housing a labyrinth is formed, which effects the pressure drop between the open atmosphere and the chamber. Labyrinth seals of this type are difficult to make with respect to the tolerances between the sealing lips and the walls of the opening roller and the housing, in particular when a wall of the housing is formed by a removable lid. Very high demands are made of the finishing accuracy.
It is an object of the present invention to seal the chamber of an opening device effectively against the open atmosphere without too high demands being made with regard to the tolerances to be observed.
This object has been achieved in accordance with the present invention in that the sealing ring is disposed on a stopping surface which determines its operational position by the action of the pressure drop present between the open atmosphere and the chamber, and in that the sealing lip, which defines the smallest diameter of the sealing ring, is larger than the diameter of the combing structure.
As a result of this design, the considerable pressure drop between the open atmosphere and the chamber is used to advantage to place the sealing lip in its operational position. Furthermore, the chosen diameter ratios make it possible to omit any form of opening roller housing lid, as the opening roller can be laterally assembled in the housing through the sealing ring. Due to the chosen width (inside diameter) of the sealing lip, there is no risk of damage to the sealing ring by the sharp combing structure. As the presence of a lid is not needed to contribute to the sealing effect, the sealing rings can be arranged on both sides of the opening roller in one and the same housing, which facilitates production.
The stopping surface defining the operational position of the sealing lip can either be arranged on the opening roller or on the housing. Should the stopping surface be arranged on the opening roller, it then preferably is formed by a bevel of a lateral collar of the opening roller. If, however, the stopping surface is arranged on the housing, the sealing lip, forming a sealing surface, is arranged on the outer circumference of a lateral collar of the opening roller.
In order to attain a good sealing effect, the sealing lip is dragged along the sealing surface during the running-in time of the sealing ring. After a few days, the sealing ring will have already ground in to such a degree that it touches the sealing surface at most very slightly, and causes no notable increase in power consumption.
In an advantageous embodiment of the present invention a floating sealing ring is provided. During the first run of the opening roller, the floating sealing ring finds its ideal position and does not normally come into contact with the sealing surface from then on.
A lateral collar of the opening roller may be provided in the area of the sealing ring, which collar forms an additional sealing gap with the housing by means of its cylindrical outer surface. The overall sealing effect is thereby increased.
A stepped collar with a larger and an adjacent smaller diameter is provided according to certain preferred embodiments, whereby the additional sealing gap is arranged at the smaller diameter and the combing structure is directly adjacent the smaller diameter. The sealing lip of the sealing ring is arranged on the larger diameter of the collar, so that during assembly of the opening roller, the combing structure cannot damage the sealing lip.
It is recommended that the sealing ring is run in already in the place of production on a special assembly device, so that during the first run of the open-end spinning machine in the spinning mill, it is ensured that all opening rollers run at the same speed and are not slowed down to any great degree by any sealing rings. If, at a later time, individual sealing rings must be replaced, this does not effect the power consumption of the open-end spinning machine in any significant way. If it were necessary to exchange all sealing rings of an open-end spinning machine at the same time, then it is recommended to let the open-end spinning machine run idle for about an hour, so that no spinning errors occur due to opening rollers rotating too slowly.